Telecommunications may be described as increasingly "feature rich." That is, there is an ever increasing array of features and services available to individual and business telephone subscribers. Many of the popular features, such as three-way calling, call forwarding and speed calling, are implemented at a local telephone switching system. Such features are generally initiated by the user signaling the local switch. For example, to set up a three-way call a user establishes a first call, flashes the switch-hook to signal the switch that three-way calling is desired, and then dials the telephone number of the third party. In response, the local switch sets up a three-way circuit.
In contrast to such locally provided features, network (also called toll or long distance) telecommunications supports a different type of features and/or services. Basic network telecommunications access is achieved through 1+ and 0+ calls; wherein 0+ calls provide a variety of credit card or operator assisted features. Other network telecommunications services (such as "800", "900" and software defined network) require that the user initiates these services by dialing a special 10 digit number. The toll switch recognizes the dialed number as a special number, performs a data base look-up (frequently based on both the dialed number and the calling line identification or "ANI"), and takes action according to the data retrieved from the data base.
At least one new feature has recently been proposed for network telecommunications that require the toll switch to recognize customer signaling: U.S. Pat. No. 4,932,042 entitled Spontaneous Voice and Data Messaging which issued Jun. 5, 1990, to Baral et al. This feature provides a calling party with the option of leaving a voice mail message after determining that the called party is busy or not answering. After a call is established, the calling party enters a series of dual-tone, multi-frequency (DTMF) signals and, in response, the toll switch routes the calling party to a voice messaging system. There is currently no implemented DTMF detector in toll switches capable of intercepting and translating these customer signals during the entire call for every call through the switch.
Another proposed network feature is sequence dialing, wherein a user may dial a second destination telephone number after a first connection is terminated without the user hanging up. This feature is useful for callers from pay telephones, credit card callers, or callers from other countries who have entered identification and billing information into the system, and need to make multiple calls. After the first called party disconnects, the caller enters one or more DTMF digits or other signals which cause the network switch to maintain the connection and then accept a new destination telephone number.
Therefore, a problem in the art is that there is no capability in network switches that can recognize customer signaling for the entire length of a network call, from pre-answer to post disconnect, for all calls in the network upon which a feature rich network may be built.